Run SSW with GDL

June 11, 2026 · View on GitHub

The idea is to make GDL pretend to be IDL.

GDL is fully syntax-compatible with IDL 7.1 and partially compatible with IDL 8.x. Due to the limited scope of our tests, compatibility with all SSW programs is not guaranteed. And we only tested our way in Linux and macOS, while this way should also work well in Windows.

Please address comments and suggestions to Dr. Luo, RunBin (罗润彬) or Dr. Chen, Jun (陈俊)

Software preparations

tcsh: https://www.tcsh.org/
SSW: http://www.lmsal.com/solarsoft/
- $SSW in the following file sswgdl is the SSW top level path, e.g. /usr/local/ssw,$HOME/ssw, C:\ssw
GDL: https://gnudatalanguage.github.io/downloads.html
- $GDL_DIR in the following file sswgdl is the GDL top level path
- if you install GDL from the software source of the system
  - command of install:
    - Ubuntu/Debian: apt install gnudatalanguage
    - Fedora: yum install gdl
    - ArchLinux: pacman -S gnudatalanguage
    - Gento: emerge gdl
    - macOS: port install gnudatalanguage or fink install gdl
  - then $GDL_DIR should be:
    - Ubuntu & Fedora: /usr/share/gnudatalanguage
    - ArchLinux: /usr/lib/gdl
    - Gentoo: /usr/local/share/gdl
    - macOS: /opt/local/share/gnudatalanguage
  - please locate the position of $command_gdl in the system
```
whereis gdl
```
    It would display /opt/local/bin/gdl in macOS, it would display /usr/bin/gdl in Ubuntu. Please execute the following command to make GDL pretend to be IDL:
```
mkdir $GDL_DIR/bin/
ln -s $command_gdl $GDL_DIR/bin/idl
```
  - $GDL_LIB in the following file sswgdl is $GDL_DIR/lib
- If you download GDL from https://github.com/gnudatalanguage/gdl/releases
  - $GDL_DIR is where you unpack the package, it should contain bin/gdl
  - please execute the following command to make GDL pretend to be IDL.
```
ln -s $GDL_DIR/bin/gdl $GDL_DIR/bin/idl
```
  - $GDL_LIB in the following file sswgdl is $GDL_DIR/share/gnudatalanguage/lib
- If you compile the project from https://github.com/gnudatalanguage/gdl
  - $GDL_DIR is where you build the project, it should contain src/gdl after the compilation
  - please execute the following command to make GDL pretend to be IDL.
```
mkdir $GDL_DIR/bin/
ln -s $GDL_DIR/src/gdl $GDL_DIR/bin/idl
```
  - $GDL_LIB in the following file sswgdl is $GDL_DIR/src/pro
- A potential issue: Launching SSW with GDL 1.0.0 will print % Cannot apply operation to datatype STRING. It is unclear which specific programs of SSW are affected, but this issue will not happen with GDL 1.1.3

Launch SSW with a script

Create a file sswgdl (can be any other name) with the following content:

#!/bin/tcsh

# please replace the text `$SSW` to the SSW top level path
setenv SSW $SSW

# Point IDL_DIR to the GDL top level path
# please replace the text `$GDL_DIR` the GDL top level path
setenv IDL_DIR $GDL_DIR

# please replace the text `$GDL_LIB` by the full path of `lib/`
setenv GDL_LIB $GDL_LIB

# Set GDL_PATH that including $SSW and your private path for *.pro
# the text `$SSW` in this line is unnessary to change
setenv GDL_PATH +$GDL_LIB/:+$SSW/:+$HOME/your/private/pro/path

# set your instruments
setenv SSW_INSTR "gen sdo aia hmi xrt hessi ontology"

# the text `$SSW` in this line is unnessary to change
source $SSW/gen/setup/setup.ssw

# Launch SSW
sswidl

Make the script executable
```
chmod u+x sswgdl
```
Launch SSW with GDL in a terminal:
```
./sswgdl
```
- note: put sswgdl to the $path of the system is suggested, e.g. you can append this line to ~/.bashrc
```
export PATH=$HOME/bin:$PATH
```
  then $HOME/bin is a $path of the system. If sswgdl is putted in a $path, you can directly run this command at any directory
```
sswgdl
```
Confirm the path inside the session
```
GDL> PRINT, !PATH
```